1. Field of the Invention
The present invention relates to a composition for preventing or treating cancers.
2. Description of the Related Art
Cancer is one of the greatest diseases threatening health of mankind and occurs when cells go through a series of mutation process, proliferate in an unlimited and uncontrollable way, and become immortal. Examples of causes of cancer include environmental or external factors such as chemicals, viruses, bacteria, ionizing radiation, etc., and internal factors such as congenital genetic mutations (Klaunig & Kamendulis, Annu Rev Pharmacol Toxicol., 44:239-267, 2004).
For cancers found in an early stage, there are therapeutic measures such as surgery, radiation therapy, chemotherapy, etc.; however, their side effects also become a big problem. For a terminal cancer or metastasized cancer, there is no specific therapeutic measure, and patients are given time-limited life and end their lives. Furthermore, various biochemical mechanisms related to cancer have been identified and the consequential therapeutic agents have been developed, however, fundamental methods for treating cancers have not yet been suggested. For this reason, efforts have been made to identify various in vivo molecules related to cancer and develop drugs which target them, and efforts have also been attempted to improve cancer-therapeutic effects by combining some of those drugs. Therefore, it is very important to endeavor to discover additional cancer-related target molecules.
SH3 domain containing ring finger 2 (SH3RF2) gene is expressed in tissues such as testis, brain, rectum, medulla, heart, lung, liver or spleen, etc., and this protein consists of 729 amino acids and includes src homology-3, SH3, zinc finger, RING-type (Pfam) and prenylation domains. The N-terminal RING domain thereof is assumed to have ubiquitin ligase activity, and this protein has three SH3 domains which bind to other proteins. SH2RF2 protein is present in various cell organelles such as mitochondria or nucleus, and regarded to perform molecular functions such as ligase activity, metal ion binding, protein binding or zinc-ion binding. However, the function of SH3RF2 has not yet been determined.
Thus, the present inventors have tried to discover new cancer-related target molecules and establish them as anticancer substances, consequently identified that the expression of SH3RF2 increases in various human tumor tissues, and SH3RF2 binds to oncogenic p21 activated kinase 4 (PAK4) to regulate an apoptosis-inhibitory function of PAK4 protein through the ubiquitination activity of SH3RF2, and inhibition of SH3RF2 expression can inhibit cancer growth, and determined that SH3RF2 inhibitors can be used as anticancer drugs or anticancer adjuvants, thereby leading to completion of the present invention.